Cutting tool, a tool body and a method for producing a tool body

Abstract

A tool body of a cutting tool includes at least one insert pocket having a bottom surface with a support face configured to provide support to a lower surface of an insert to be received in the pocket and having at least one cutting edge formed between a top surface and a side surface connecting the lower surface and the top surface. The bottom surface of the pocket has a countersunk central portion surrounded by a peripheral bottom surface portion configured to form the only support face of the bottom surface to the lower surface of an insert to be received in the pocket.

1 . A cutting tool, comprising:
 a tool body having at least one pocket;   at least one cutting insert releasably fixed to the pocket, the insert having a lower surface, a top surface, a surrounding side surface connecting the lower surface and the top surface and at least one cutting edge formed between the top surface and the side surface, the pocket having a bottom surface with a support face configured to provide support to the lower surface of the insert, and   a fastening device configured to secure the insert in the pocket while pressing portions of the lower surface of the insert against the support face, wherein the bottom surface of the pocket has a countersunk central portion has a design arranged to keep the lower surface of the insert to be received in the pocket out of contact therewith and a peripheral portion surrounding the central portion configured to provide the only support face for the lower surface of the insert by supporting a portion of the lower surface of the insert bearing thereupon.   
     
     
         2 . The cutting tool according to  claim 1 , wherein the cutting insert has a flat lower surface. 
     
     
         3 . The cutting tool according to  claim 1 , wherein a maximum distance between and perpendicular to the bottom surface of the pocket of the countersunk central portion to the support face of the peripheral portion is≥5×10 −3 ×a largest dimension of the bottom surface. 
     
     
         4 . The cutting tool according to  claim 1 , wherein a maximum distance between and perpendicular to the bottom surface of the pocket of the countersunk central portion to the support face of the peripheral portion is ≤1.0×10 −1 ×a largest dimension of the bottom surface or ≤5×10 −2 ×the largest dimension of the bottom surface. 
     
     
         5 . The cutting tool according to any of the preceding claims  claim 1 , wherein the cutting insert has a central through-hole from the top surface to the lower surface thereof for securing the insert in the pocket by the fastening device, the fastening device being a screw penetrating into a hole with an inner thread, the hole being located in the central portion of the bottom surface of the pocket. 
     
     
         6 . The cutting tool according to  claim 1 , wherein the lower surface of the cutting insert is convex, and that the countersunk central portion of the bottom surface of the pocket is more concave than the lower surface of the insert is convex so as to be out of contact therewith. 
     
     
         7 . The cutting tool according to  claim 1 , wherein the cutting insert is double-sided with at least one cutting edge formed also between the lower surface and the side surface thereof. 
     
     
         8 . The cutting tool according to  claim 7 , wherein the cutting edges of the cutting insert are raised with respect to an adjacent top and lower surface of the insert. 
     
     
         9 . A tool body of a cutting tool, comprising at least one insert pocket having a bottom surface with a support face configured to provide support to a lower surface of an insert to be received in said pocket and having at least one cutting edge formed between top surface and a side surface connecting the lower surface and the top surface, wherein the bottom surface of the pocket has a countersunk central portion surrounded by a peripheral bottom surface portion configured to form the only support face of the bottom surface to the lower surface of an insert to be received in the pocket. 
     
     
         10 . The tool body according to  claim 9 , wherein the bottom surface of the pocket has a wave structure. 
     
     
         11 . The tool body according to  claim 10 , wherein the depths of the waves of said wave structure, the depth being a distance between a top separating two valleys and a bottom of a valley, is ≤0.05 mm. 
     
     
         12 . The tool body according to  claim 9 , wherein the central portion of the bottom surface of the pocket has a depth with respect to the support face of the peripheral bottom surface portion starting at a border to the support face and increasing with the distance from this the support face. 
     
     
         13 . The tool body according to  claim 9 , wherein the central portion of the bottom surface of the pocket defines a recess in the bottom surface with a conical or frustoconical shape. 
     
     
         14 . The tool body according to  claim 9 , wherein the central portion of the bottom surface of the pocket extends towards the peripheral portion providing the support face along an arc with a centre above the central portion. 
     
     
         15 . The tool body according to  claim 9 , wherein the central portion of the bottom surface of the pocket extends towards the peripheral portion providing the support face along an arc with a centre below the central portion. 
     
     
         16 . The tool body according to  claim 9 , wherein the bottom surface of the pocket has a step separating the support face of the peripheral bottom surface portion from the central portion and making this countersunk with respect to the peripheral bottom surface portion. 
     
     
         17 . The tool body according to  claim 16 , wherein the step is formed by walls of the bottom surface extending from the central portion while making an angle of 70°-95° or 80°-90° therewith. 
     
     
         18 . A method for producing a tool body according to any of claims  claim 9 , comprising the steps of
 subjecting a central portion of the bottom surface of the at least one pocket to treatment by a ball nose cutter; and   removing material therefrom to form a countersunk central portion surrounded by a peripheral bottom surface portion so as to make the bottom surface to provide an insert support face only by this peripheral bottom surface portion.